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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 104 Abstracts search results
Document:
21-458
Date:
January 1, 2023
Author(s):
Duo Zhang and Victor C. Li
Publication:
Materials Journal
Volume:
120
Issue:
1
Abstract:
The built environment is facing an increasing challenge of reducing emissions regarding both embodied and operational carbon. As an ultra-durable concrete, engineered cementitious composites (ECC) reduce the need for repair, thus resulting in a prominent reduction of life-cycle footprints. Herein, a new version of low-carbon ECC was developed for cast-in-place applications by sequestering CO2 through mineralization. Two waste streams were pre-carbonated and incorporated into ECC as fine aggregate and supplementary cementitious material, respectively. At 28 days, the CO2-sequestered ECC exhibited a compressive strength of 32.2 MPa (4670 psi), tensile strength of 3.5 MPa (508 psi), and strain capacity of 2.9%. Multiple fine cracks were distinctly identified, with a residual crack width of 38 μm (0.0015 in.) and a selfhealing behavior comparable to that of conventional ECC. The new ECC sequestered 97.7 kg/m3 (164.7 lb/yd3) CO2 (equivalent to 4.7 wt% of final mixture) and demonstrated a 42% reduction in cradle-to-gate emissions compared to conventional concrete at the same strength level. This study demonstrates the viability of turning waste CO2 gas into durable construction materials and proposes a potential path towards carbon neutrality.
DOI:
10.14359/51737331
22-043
November 1, 2022
W. K. Toledo, A. Alvarez, G. J. Gonzales, C. M. Newtson, and B. D. Weldon
119
6
This work investigated the effects of substrate surface moisture condition and texture on ultra-high-performance concrete overlay bond strength. This investigation was performed in three parts that studied extreme substrate moisture conditions, partially dried substrate moisture conditions, and surface texture. These studies investigated the effects of substrate surface moisture conditions, from dry to a surface with a thin layer of free moisture, and surface textures that provided various aggregate exposure conditions on overlay bond strength. Direct tension pull-off tests were conducted to assess overlay bond strength. Results for specimens with exposed fine aggregate surface textures showed that visibly moist substrate surfaces facilitated development of excellent bond strengths, and adequate bond was achieved for conditions with a thin layer of free moisture. For specimens with saturated surface-dry conditions, acceptable bond was achieved with a slightly exposed fine aggregate texture and increasing bond strength was observed with increasing aggregate exposure.
10.14359/51736004
21-298
May 1, 2022
Keikhosrow Tahmureszadeh, Medhat H. Shehata, and Bill Gong
3
The durability of three repair materials was investigated under two exposures: freezing-and-thawing cycles in the presence of deicing salts, and substrate undergoing expansion due to alkali-aggregate reaction (AAR). The bond strength of the repairs under freezing-and-thawing exposure was evaluated using slant shear, splitting tensile, and pulloff tests. Additionally, the pulloff test was implemented to investigate the bond strength of repairs undergoing expansion due to AAR. Under freezing and thawing, the substrate surface roughness was evaluated and resulted in a higher bond strength under combined shear and compression forces (slant shear test). The results for both exposures showed that the efficacy of a repair could not only be explained based on the net unrestrained length change between the repair and the substrate. While significant autogenous shrinkage of ultra-high-performance concrete (UHPC) can increase the net unrestrained length change, the strength, fibers, and high paste content of such material enhance the bond strength.
10.14359/51734614
21-184
March 1, 2022
A. Azzam, M. T. Bassuoni, and A. Shalaby
2
There is constant demand for high-performance materials to build and rehabilitate concrete infrastructure. The current study investigated the properties of nano-modified cementitious composites incorporating emerging basalt fiber pellets (BFP), including their suitability as repair/overlay for concrete. The composites comprised 50% cement replacement with fly ash or slag, 6% nanosilica addition, and two BFP dosages (2.5 and 4.5% by volume). They were assessed in terms of fresh and hardened properties, as well as their compatibility with concrete substrate. Furthermore, microstructural and thermal analyses were performed to evaluate the evolution of microstructure and interpret the bulk trends. The results showed that the composites had high strength, ductility, and resistance to infiltration of fluids. BFP effectively contributed to the dimensional stability of the composites, which had high thermal and elastic compatibility with concrete substrate even after an aggravated exposure. Hence, they may offer an attractive option as high-performance repair/overlay materials for concrete.
10.14359/51734442
21-084
Dong-Hyuk Kim, Woo-Sung Yum, Jun-Young Park, Moon-Gyu Choi, and Jin-Hoon Jeong
In this study, an optimal curing method was established for very early-strength latex-modified concrete (VES-LMC), which is frequently used in partial-depth repair (PDR) of deteriorated concrete pavements. The appropriate starting time of curing, when the surface of the VES-LMC was not damaged, was found for various curing conditions such as ambient air, polyethylene (PE) sheet, blanket, curing membrane, PE sheet on curing membrane, and blanket on curing membrane. The hydration characteristics of the VES-LMC and ordinary portland cement concrete (OPCC) were then compared by evaluating their respective properties such as water loss, bleeding, autogenous shrinkage, and compressive strength. In addition, the optimal curing method was investigated by determining the water loss, water absorption, drying shrinkage, and compressive strength of the VES-LMC specimens cured under the aforementioned conditions. The test results revealed that VES-LMC performed better than OPCC as a PDR material. In addition, covering the VES-LMC with a PE sheet 3 minutes after placement was observed to be the most effective curing method in PDR.
10.14359/51734223
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